Interference can happen for two adjacent processing chambers (e.g., physical vapor deposition (PVD) chambers). The magnetic field from one chamber can affect the magnetic field in an adjacent chamber, resulting in deposition rate, uniformity and/or deposition profile differences.
With the application or use of an electromagnet (EM), the EM current can generate a strong field, which can lead to the possibility of EM interference. With a small EM current, the generated magnetic field (B-field) can be small enough to not cause measurable or significant interference. An interlock can be set to ensure that the EM current/B-field is under a threshold value that does not cause interference. However, for processes using large electric currents, interference between adjacent chambers are observed and can be significant in impact.
Currently, magnetic shields are used to reduce interference; however, magnetic shields cannot eliminate interference. The effectiveness of B-shield materials are directly related to the thickness/volume of the material. To eliminate interference, the B-shield would be extraordinarily bulky, expensive and not serviceable.
Therefore, there is a need in the art for methods and apparatus to reduce or eliminate magnetic field interference.